I'm not sure if this works with server-side languages other than php, but if you pass key/value pairs where the key has a [something] appended to its name, php will convert it into an array where "something" becomes an index.

So, if you want to pass a multi-dimensional array when posting, you could do something like this:

Let's say you want to pass something like this:

var options = {
"a":"1",
"b":{"I":"1", "II":"2"},
}

So that you receive this on server-side (in php in my case):

array(
"a"=>"1",
"b"=>array(
"I"=>"1",
"II"=>"2"
)
)

You could pass this in your post:

var options = {
"a":"1",
"b[I]":"1",
"b[II]":"2"
}

It may need a bit of manual parsing in javascript if you had a pre-constructed object you want to pass, but that's easy enough to do using the "for (key in object) {}" method...